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121 lines
3.0 KiB
Objective-C
121 lines
3.0 KiB
Objective-C
#include "objc/runtime.h"
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#include "lock.h"
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#include <stdio.h>
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#include <stdlib.h>
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int snprintf(char *restrict s, size_t n, const char *restrict format, ...);
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@interface Fake
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+ (void)dealloc;
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@end
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static mutex_t at_sync_init_lock;
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static unsigned long long lockClassId;
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void __objc_sync_init(void)
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{
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INIT_LOCK(at_sync_init_lock);
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}
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IMP objc_msg_lookup(id, SEL);
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static void deallocLockClass(id obj, SEL _cmd);
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static inline Class findLockClass(id obj)
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{
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struct objc_object object = { obj->isa };
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SEL dealloc = @selector(dealloc);
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// Find the first class where this lookup is correct
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if (objc_msg_lookup((id)&object, dealloc) != (IMP)deallocLockClass)
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{
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do {
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object.isa = class_getSuperclass(object.isa);
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} while (Nil != object.isa &&
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objc_msg_lookup((id)&object, dealloc) != (IMP)deallocLockClass);
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}
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if (Nil == object.isa) { return Nil; }
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// object->isa is now either the lock class, or a class which inherits from
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// the lock class
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Class lastClass;
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do {
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lastClass = object.isa;
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object.isa = class_getSuperclass(object.isa);
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} while (Nil != object.isa &&
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objc_msg_lookup((id)&object, dealloc) == (IMP)deallocLockClass);
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return lastClass;
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}
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static inline Class initLockObject(id obj)
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{
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Class lockClass;
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if (class_isMetaClass(obj->isa))
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{
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lockClass = objc_allocateMetaClass(obj, sizeof(mutex_t));
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}
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else
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{
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char nameBuffer[40];
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snprintf(nameBuffer, 39, "hiddenlockClass%lld", lockClassId++);
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lockClass = objc_allocateClassPair(obj->isa, nameBuffer,
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sizeof(mutex_t));
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}
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const char *types =
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method_getTypeEncoding(class_getInstanceMethod(obj->isa,
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@selector(dealloc)));
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class_addMethod(lockClass, @selector(dealloc), (IMP)deallocLockClass,
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types);
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if (!class_isMetaClass(obj->isa))
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{
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objc_registerClassPair(lockClass);
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}
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mutex_t *lock = object_getIndexedIvars(lockClass);
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INIT_LOCK(*lock);
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obj->isa = lockClass;
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return lockClass;
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}
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static void deallocLockClass(id obj, SEL _cmd)
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{
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Class lockClass = findLockClass(obj);
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Class realClass = class_getSuperclass(lockClass);
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// Call the real -dealloc method
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struct objc_super super = {obj, realClass };
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objc_msgSendSuper(&super, @selector(dealloc));
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// After calling [super dealloc], the object will no longer exist.
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// Free the lock
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mutex_t *lock = object_getIndexedIvars(lockClass);
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DESTROY_LOCK(lock);
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// Free the class
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objc_disposeClassPair(lockClass);
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}
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// TODO: This should probably have a special case for classes conforming to the
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// NSLocking protocol, just sending them a -lock message.
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void objc_sync_enter(id obj)
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{
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Class lockClass = findLockClass(obj);
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if (Nil == lockClass)
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{
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LOCK(&at_sync_init_lock);
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// Test again in case two threads call objc_sync_enter at once
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lockClass = findLockClass(obj);
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if (Nil == lockClass)
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{
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lockClass = initLockObject(obj);
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}
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UNLOCK(&at_sync_init_lock);
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}
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mutex_t *lock = object_getIndexedIvars(lockClass);
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LOCK(lock);
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}
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void objc_sync_exit(id obj)
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{
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Class lockClass = findLockClass(obj);
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mutex_t *lock = object_getIndexedIvars(lockClass);
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UNLOCK(lock);
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}
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